Makefile.build 12.1 KB
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# ==========================================================================
# Building
# ==========================================================================

src := $(obj)

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PHONY := __build
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__build:

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# Init all relevant variables used in kbuild files so
# 1) they have correct type
# 2) they do not inherit any value from the environment
obj-y :=
obj-m :=
lib-y :=
lib-m :=
always :=
targets :=
subdir-y :=
subdir-m :=
EXTRA_AFLAGS   :=
EXTRA_CFLAGS   :=
EXTRA_CPPFLAGS :=
EXTRA_LDFLAGS  :=
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asflags-y  :=
ccflags-y  :=
cppflags-y :=
ldflags-y  :=
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subdir-asflags-y :=
subdir-ccflags-y :=

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# Read auto.conf if it exists, otherwise ignore
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-include include/config/auto.conf
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include scripts/Kbuild.include

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# For backward compatibility check that these variables do not change
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save-cflags := $(CFLAGS)

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# The filename Kbuild has precedence over Makefile
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kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
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kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)
include $(kbuild-file)

# If the save-* variables changed error out
ifeq ($(KBUILD_NOPEDANTIC),)
        ifneq ("$(save-cflags)","$(CFLAGS)")
                $(error CFLAGS was changed in "$(kbuild-file)". Fix it to use EXTRA_CFLAGS)
        endif
endif
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include scripts/Makefile.lib

ifdef host-progs
ifneq ($(hostprogs-y),$(host-progs))
$(warning kbuild: $(obj)/Makefile - Usage of host-progs is deprecated. Please replace with hostprogs-y!)
hostprogs-y += $(host-progs)
endif
endif

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# Do not include host rules unless needed
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ifneq ($(hostprogs-y)$(hostprogs-m),)
include scripts/Makefile.host
endif

ifneq ($(KBUILD_SRC),)
# Create output directory if not already present
_dummy := $(shell [ -d $(obj) ] || mkdir -p $(obj))

# Create directories for object files if directory does not exist
# Needed when obj-y := dir/file.o syntax is used
_dummy := $(foreach d,$(obj-dirs), $(shell [ -d $(d) ] || mkdir -p $(d)))
endif

ifndef obj
$(warning kbuild: Makefile.build is included improperly)
endif

# ===========================================================================

ifneq ($(strip $(lib-y) $(lib-m) $(lib-n) $(lib-)),)
lib-target := $(obj)/lib.a
endif

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ifneq ($(strip $(obj-y) $(obj-m) $(obj-n) $(obj-) $(subdir-m) $(lib-target)),)
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builtin-target := $(obj)/built-in.o
endif

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modorder-target := $(obj)/modules.order

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# We keep a list of all modules in $(MODVERDIR)

__build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
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	 $(if $(KBUILD_MODULES),$(obj-m) $(modorder-target)) \
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	 $(subdir-ym) $(always)
	@:

# Linus' kernel sanity checking tool
ifneq ($(KBUILD_CHECKSRC),0)
  ifeq ($(KBUILD_CHECKSRC),2)
    quiet_cmd_force_checksrc = CHECK   $<
          cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
  else
      quiet_cmd_checksrc     = CHECK   $<
            cmd_checksrc     = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
  endif
endif

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# Do section mismatch analysis for each module/built-in.o
ifdef CONFIG_DEBUG_SECTION_MISMATCH
  cmd_secanalysis = ; scripts/mod/modpost $@
endif
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# Compile C sources (.c)
# ---------------------------------------------------------------------------

# Default is built-in, unless we know otherwise
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modkern_cflags =                                          \
	$(if $(part-of-module),                           \
		$(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE), \
		$(CFLAGS_KERNEL))
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quiet_modtag := $(empty)   $(empty)

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$(real-objs-m)        : part-of-module := y
$(real-objs-m:.o=.i)  : part-of-module := y
$(real-objs-m:.o=.s)  : part-of-module := y
$(real-objs-m:.o=.lst): part-of-module := y
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$(real-objs-m)        : quiet_modtag := [M]
$(real-objs-m:.o=.i)  : quiet_modtag := [M]
$(real-objs-m:.o=.s)  : quiet_modtag := [M]
$(real-objs-m:.o=.lst): quiet_modtag := [M]

$(obj-m)              : quiet_modtag := [M]

# Default for not multi-part modules
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modname = $(basetarget)
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$(multi-objs-m)         : modname = $(modname-multi)
$(multi-objs-m:.o=.i)   : modname = $(modname-multi)
$(multi-objs-m:.o=.s)   : modname = $(modname-multi)
$(multi-objs-m:.o=.lst) : modname = $(modname-multi)
$(multi-objs-y)         : modname = $(modname-multi)
$(multi-objs-y:.o=.i)   : modname = $(modname-multi)
$(multi-objs-y:.o=.s)   : modname = $(modname-multi)
$(multi-objs-y:.o=.lst) : modname = $(modname-multi)

quiet_cmd_cc_s_c = CC $(quiet_modtag)  $@
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cmd_cc_s_c       = $(CC) $(c_flags) -fverbose-asm -S -o $@ $<
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$(obj)/%.s: $(src)/%.c FORCE
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	$(call if_changed_dep,cc_s_c)

quiet_cmd_cc_i_c = CPP $(quiet_modtag) $@
cmd_cc_i_c       = $(CPP) $(c_flags)   -o $@ $<

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$(obj)/%.i: $(src)/%.c FORCE
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	$(call if_changed_dep,cc_i_c)

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cmd_gensymtypes =                                                           \
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    $(CPP) -D__GENKSYMS__ $(c_flags) $< |                                   \
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    $(GENKSYMS) $(if $(1), -T $(2)) -a $(ARCH)                              \
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     $(if $(KBUILD_PRESERVE),-p)                                            \
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     -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
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quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
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cmd_cc_symtypes_c =                                                         \
    set -e;                                                                 \
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    $(call cmd_gensymtypes,true,$@) >/dev/null;                             \
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    test -s $@ || rm -f $@
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$(obj)/%.symtypes : $(src)/%.c FORCE
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	$(call cmd,cc_symtypes_c)
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# C (.c) files
# The C file is compiled and updated dependency information is generated.
# (See cmd_cc_o_c + relevant part of rule_cc_o_c)

quiet_cmd_cc_o_c = CC $(quiet_modtag)  $@

ifndef CONFIG_MODVERSIONS
cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<

else
# When module versioning is enabled the following steps are executed:
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# o compile a .tmp_<file>.o from <file>.c
# o if .tmp_<file>.o doesn't contain a __ksymtab version, i.e. does
#   not export symbols, we just rename .tmp_<file>.o to <file>.o and
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#   are done.
# o otherwise, we calculate symbol versions using the good old
#   genksyms on the preprocessed source and postprocess them in a way
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#   that they are usable as a linker script
# o generate <file>.o from .tmp_<file>.o using the linker to
#   replace the unresolved symbols __crc_exported_symbol with
#   the actual value of the checksum generated by genksyms
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cmd_cc_o_c = $(CC) $(c_flags) -c -o $(@D)/.tmp_$(@F) $<
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cmd_modversions =								\
	if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then		\
		$(call cmd_gensymtypes,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
		    > $(@D)/.tmp_$(@F:.o=.ver);					\
										\
		$(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) 			\
			-T $(@D)/.tmp_$(@F:.o=.ver);				\
		rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver);		\
	else									\
		mv -f $(@D)/.tmp_$(@F) $@;					\
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	fi;
endif

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ifdef CONFIG_FTRACE_MCOUNT_RECORD
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cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
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	"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
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	"$(if $(CONFIG_64BIT),64,32)" \
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	"$(OBJDUMP)" "$(OBJCOPY)" "$(CC)" "$(LD)" "$(NM)" "$(RM)" "$(MV)" \
	"$(if $(part-of-module),1,0)" "$(@)";
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endif

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define rule_cc_o_c
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	$(call echo-cmd,checksrc) $(cmd_checksrc)			  \
	$(call echo-cmd,cc_o_c) $(cmd_cc_o_c);				  \
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	$(cmd_modversions)						  \
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	$(call echo-cmd,record_mcount)					  \
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	$(cmd_record_mcount)						  \
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	scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' >    \
	                                              $(dot-target).tmp;  \
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	rm -f $(depfile);						  \
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	mv -f $(dot-target).tmp $(dot-target).cmd
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endef

# Built-in and composite module parts
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$(obj)/%.o: $(src)/%.c FORCE
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	$(call cmd,force_checksrc)
	$(call if_changed_rule,cc_o_c)

# Single-part modules are special since we need to mark them in $(MODVERDIR)

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$(single-used-m): $(obj)/%.o: $(src)/%.c FORCE
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	$(call cmd,force_checksrc)
	$(call if_changed_rule,cc_o_c)
	@{ echo $(@:.o=.ko); echo $@; } > $(MODVERDIR)/$(@F:.o=.mod)

quiet_cmd_cc_lst_c = MKLST   $@
      cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
		     $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
				     System.map $(OBJDUMP) > $@

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$(obj)/%.lst: $(src)/%.c FORCE
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	$(call if_changed_dep,cc_lst_c)

# Compile assembler sources (.S)
# ---------------------------------------------------------------------------

modkern_aflags := $(AFLAGS_KERNEL)

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$(real-objs-m)      : modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
$(real-objs-m:.o=.s): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
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quiet_cmd_as_s_S = CPP $(quiet_modtag) $@
cmd_as_s_S       = $(CPP) $(a_flags)   -o $@ $< 

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$(obj)/%.s: $(src)/%.S FORCE
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	$(call if_changed_dep,as_s_S)

quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
cmd_as_o_S       = $(CC) $(a_flags) -c -o $@ $<

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$(obj)/%.o: $(src)/%.S FORCE
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	$(call if_changed_dep,as_o_S)

targets += $(real-objs-y) $(real-objs-m) $(lib-y)
targets += $(extra-y) $(MAKECMDGOALS) $(always)

# Linker scripts preprocessor (.lds.S -> .lds)
# ---------------------------------------------------------------------------
quiet_cmd_cpp_lds_S = LDS     $@
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      cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -C -U$(ARCH) \
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	                     -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
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$(obj)/%.lds: $(src)/%.lds.S FORCE
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	$(call if_changed_dep,cpp_lds_S)

# Build the compiled-in targets
# ---------------------------------------------------------------------------

# To build objects in subdirs, we need to descend into the directories
$(sort $(subdir-obj-y)): $(subdir-ym) ;

#
# Rule to compile a set of .o files into one .o file
#
ifdef builtin-target
quiet_cmd_link_o_target = LD      $@
# If the list of objects to link is empty, just create an empty built-in.o
cmd_link_o_target = $(if $(strip $(obj-y)),\
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		      $(LD) $(ld_flags) -r -o $@ $(filter $(obj-y), $^) \
		      $(cmd_secanalysis),\
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		      rm -f $@; $(AR) rcs $@)

$(builtin-target): $(obj-y) FORCE
	$(call if_changed,link_o_target)

targets += $(builtin-target)
endif # builtin-target

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#
# Rule to create modules.order file
#
# Create commands to either record .ko file or cat modules.order from
# a subdirectory
modorder-cmds =						\
	$(foreach m, $(modorder),			\
		$(if $(filter %/modules.order, $m),	\
			cat $m;, echo kernel/$m;))

$(modorder-target): $(subdir-ym) FORCE
	$(Q)(cat /dev/null; $(modorder-cmds)) > $@

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#
# Rule to compile a set of .o files into one .a file
#
ifdef lib-target
quiet_cmd_link_l_target = AR      $@
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cmd_link_l_target = rm -f $@; $(AR) rcs $@ $(lib-y)
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$(lib-target): $(lib-y) FORCE
	$(call if_changed,link_l_target)

targets += $(lib-target)
endif

#
# Rule to link composite objects
#
#  Composite objects are specified in kbuild makefile as follows:
#    <composite-object>-objs := <list of .o files>
#  or
#    <composite-object>-y    := <list of .o files>
link_multi_deps =                     \
$(filter $(addprefix $(obj)/,         \
$($(subst $(obj)/,,$(@:.o=-objs)))    \
$($(subst $(obj)/,,$(@:.o=-y)))), $^)
 
quiet_cmd_link_multi-y = LD      $@
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cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis)
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quiet_cmd_link_multi-m = LD [M]  $@
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cmd_link_multi-m = $(cmd_link_multi-y)
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# We would rather have a list of rules like
# 	foo.o: $(foo-objs)
# but that's not so easy, so we rather make all composite objects depend
# on the set of all their parts
$(multi-used-y) : %.o: $(multi-objs-y) FORCE
	$(call if_changed,link_multi-y)

$(multi-used-m) : %.o: $(multi-objs-m) FORCE
	$(call if_changed,link_multi-m)
	@{ echo $(@:.o=.ko); echo $(link_multi_deps); } > $(MODVERDIR)/$(@F:.o=.mod)

targets += $(multi-used-y) $(multi-used-m)


# Descending
# ---------------------------------------------------------------------------

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PHONY += $(subdir-ym)
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$(subdir-ym):
	$(Q)$(MAKE) $(build)=$@

# Add FORCE to the prequisites of a target to force it to be always rebuilt.
# ---------------------------------------------------------------------------

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PHONY += FORCE
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FORCE:

# Read all saved command lines and dependencies for the $(targets) we
# may be building above, using $(if_changed{,_dep}). As an
# optimization, we don't need to read them if the target does not
# exist, we will rebuild anyway in that case.

targets := $(wildcard $(sort $(targets)))
cmd_files := $(wildcard $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))

ifneq ($(cmd_files),)
  include $(cmd_files)
endif
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# Declare the contents of the .PHONY variable as phony.  We keep that
# information in a variable se we can use it in if_changed and friends.

.PHONY: $(PHONY)